The present invention relates to an illuminating angle adjusting apparatus to be used in an electronic flash device for photography.
In conventional illuminating angle adjusting apparatuses i.e., shown in FIGS. 8 and 9, a zooming frame (1) carrying an optical lens at the front end thereof is electrically driven by a motor (2). A transmission mechanism (4) which transmits the driving force of the motor is provided between two inner lateral side surfaces of the zooming frame (1) and above the upper surface of a light emitting portion (5). Moreover, a pair of rack gears (6), (6) stationarily provided on the upper internal surfaces of the right and left side walls (1a), (1b) of the zooming frame (1) are engaged with corresponding output gears (4a), (4b) of the transmission mechanism (4) at a plane (a) which is in the almost the same plane as the upper surface of the light emitting portion (5). The plane (a) is defined as being such a plane in which the transmission of the driving force from the transmission mechanism to the rack gears is carried out. As shown in FIG. 8, guide grooves (8), (8) for guiding the zooming frame are further provided below the plane (a) and at the center of lateral side walls of the light emitting portion (5). When the motor (2) is driven, a driving force is transmitted to the rack gears (6), (6) of the zooming frame (1) through the transmission mechanism (4) to move the zooming frame (1) along the guide groove (8). This movement of the zooming frame changes the clearance or separation between the light emitting portion (5) and the optical lens and thereby causes a change in the illuminating angle of the electronic flash device.
The guide grooves (8), (8) for guiding the zooming frame are provided at the area spaced by the distance (l) from the plane (a), so that a large moment is applied on the guide grooves (8), (8) due to the positional difference between the plane (a) and the guide grooves (8), (8) by the distance (l). Thereby a large frictional force is generated at the guide grooves, resulting in a disadvantage that the zooming frame (1) cannot move smoothly.